linux-kernel - Re: [PATCH V2 1/9] perf tools: add test for reading object code

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Date:	Wed, 31 Jul 2013 14:28:33 -0300
From:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
To:	Adrian Hunter <adrian.hunter@...el.com>
Cc:	linux-kernel@...r.kernel.org, David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jiri Olsa <jolsa@...hat.com>, Mike Galbraith <efault@....de>,
	Namhyung Kim <namhyung@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Stephane Eranian <eranian@...gle.com>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH V2 1/9] perf tools: add test for reading object code

Em Wed, Jul 31, 2013 at 11:58:20AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Wed, Jul 31, 2013 at 12:13:50AM +0300, Adrian Hunter escreveu:
> > Using the information in mmap events, perf tools can read object
> > code associated with sampled addresses.  A test is added that
> > compares bytes read by perf with the same bytes read using
> > objdump.
> 
> investigating...
> 
> (gdb) run test 21
> Starting program: /root/bin/perf test 21
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib64/libthread_db.so.1".
> 21: Test object code reading                               :
> Program received signal SIGSEGV, Segmentation fault.
> 0x000000000045a2d3 in xyarray__entry (xy=0x0, x=0, y=0) at util/xyarray.h:17
> 17		return &xy->contents[x * xy->row_size + y * xy->entry_size];


Still investigating, but the attached patch is needed to handle such
failure cases:

[root@zoo ~]# perf test 21
21: Test object code reading                               : FAILED!
[root@zoo ~]# perf test -v 21
21: Test object code reading                               :
--- start ---
Looking at the vmlinux_path (6 entries long)
symsrc__init: cannot get elf header.
Using /lib/modules/3.11.0-rc2+/build/vmlinux for symbols
Parsing event 'cycles'
Parsing event 'cycles:u'
perf_evlist__open failed
---- end ----
Test object code reading: FAILED!
[root@zoo ~]# 

- Arnaldo

View attachment "error_path.patch" of type "text/plain" (3485 bytes)